Transposable elements are segments of DNA that can change their chromosomal location in the genome of the host. They are found in all organisms, and their unique genetic properties have profound implications for the evolution of species from bacteria to higher plants and animals, including man. The long term goal of this research is to understand transposable elements in the nematode worm Caenorhabditis elegans. C. elegans is a simple metazoan suitable for the study of many fundamental questions in biology. Basic studies in such model systems provide the new knowledge upon which advances in medicine depend. In this research two newly discovered, putative transposable elements will be characterized at the DNA sequence level. Their structure will be compared to that of the many other known elements in other organisms. In addition, RNA and protein products of these sequences and of the previously characterized transposable element Tcl will be studied. The purpose is to identify the protein factors, transposases, that catalyze the movement of these elements, and to study their regulation. The information obtained will be used to construct novel, synthetic transposable elements with properties that can be exploited in genetic experiments with C. elegans. These experiments involve isolation of genes by transposon tagging and DNA-mediated transformation.